flats.js

var foundFlat = null;
var foundFloor = null;

_.each(json, function(bulk) {
    _.each(bulk.sections, function(section) {
        _.each(section.floors, function(floor, floorData) {
            if (floorData.flats) {
                _.each(floorData.flats, function(flat) {
                    if (flat.id === flatId) {
                        foundFlat = flat;
                        foundFloor = floor;
                    }
                });
            }
        });
    });
});